This research is devoted to studies of the physiological consequences of coronary artery stenosis in instrumented animal models. Animals are instrumented at sterile surgery for measurement of coronary artery flow and regional myocardial function. Following recovery from the surgical implantation, the left circumflex coronary artery is occluded gradually or intermittently in sequences designed to produce various degrees of myocardial ischemia and to stimulate the development of coronary collateral flow channels. The goals of the experiments are to determine the natural history of progression of obstructive coronary artery disease, to characterize the function and control of the resultant coronary collateral arteries, and to provide experimental bases for therapies designed to ameliorate the debilitating consequences of coronary artery disease.